Ibn Majah

Commentary:
(1)
The senior Companions (radi Allahu anhum) performed unparalleled feats in the service and defense of Islam; therefore, every person who loves Islam holds affection and esteem for them in his heart. And for the enemies of Islam, their very existence was a torment to the soul. Among such great individuals is also Ali (radi Allahu anhu); thus, loving him is a sign of faith, and enmity towards him is a sign of hypocrisy.

(2)
By love is not meant the excessiveness (ghuluww) found among some people of innovation (ahl al-bid‘ah), for example:
Some have declared Ali (radi Allahu anhu) to be infallible like the Prophets.
Some have considered him superior to Abu Bakr and Umar (radi Allahu anhuma).
Some have attributed divine attributes to him, and some have even declared him to be God Himself who descended to earth in human form.
Similarly, making vows and offerings (nadhar-o-niyaz) in the name of Ali (radi Allahu anhu), calling upon him in times of hardship and difficulty, chanting slogans such as "Ya Ali, Ya Ali madad," reciting invocations like Nad-e-Ali, or forming the shape of a hand with five fingers and considering it to be the hand of Ali (radi Allahu anhu) and a means of resolving difficulties—all these are acts of shirk (polytheism), neither commanded by Ali (radi Allahu anhu) nor is he pleased with them.
These matters have no connection whatsoever with that love which is a sign of faith.

(3)
The differences that occurred among the Companions (radi Allahu anhum) were differences of ijtihad (independent juristic reasoning), although, due to the conspiracies of the hypocrites, the result of some of these differences even manifested in the form of fighting and conflict.
To declare any Companion a hypocrite because of these disputes is a great audacity and is a sign of the people of innovation (ahl al-bid‘ah).
According to the Ahl al-Sunnah, regarding these disputes, withholding the tongue (kaf al-lisan)—that is, remaining silent and not declaring one another to be in error—is better.

Hadith Commentary: Benefits and Issues:
If a person, knowing the status of Ali (radi Allahu anhu)—that he was the cousin and son-in-law of the Prophet (sallallahu alayhi wa sallam), that the Prophet (sallallahu alayhi wa sallam) loved him, that he (sallallahu alayhi wa sallam) raised him in childhood, and that he was among the very first to embrace Islam, and that he sacrificed everything for the sake of Islam—still harbors hatred and enmity towards him, then this is clear evidence that such a person harbors enmity towards Islam and the Messenger of Allah (sallallahu alayhi wa sallam), and does not like the dominance and spread of Islam.

If, due to the aforementioned reasons, one holds feelings of love and devotion, then this is a sign that he loves Islam, the Messenger, and the dominance of Islam, and these things bring him joy; therefore, he is a believer.

However, if there is enmity or disagreement due to some personal, political, or familial reason—as sometimes disagreements and displeasure arose between Fatimah (radi Allahu anha) and Ali (radi Allahu anhu), or between the two Shaykhs (radi Allahu anhuma) and Ali (radi Allahu anhu), and other Companions (radi Allahu anhum)—then such matters are not contrary to faith.

Explanation:
1:
What is meant here is legal (shar‘i) love and enmity.
For example, if a person loves Ali (radi Allahu anhu) but harbors enmity towards Abu Bakr and Umar (radi Allahu anhuma), then his love is not a sign of faith (iman).
And as for the matter of enmity,
then harboring enmity towards Ali (radi Allahu anhu) alone is sufficient to negate faith,
even if he loves Abu Bakr, Umar, and Uthman (radi Allahu anhum).

2:
That is: The statement of the Prophet (sallallahu alayhi wa sallam), “O Allah, love the one who loves Ali,”
means that I am included among those for whom this prophetic supplication applies, because I love Ali (radi Allahu anhu).

(1) "The Unlettered Prophet" — 'Unlettered' is that great attribute of yours which was also recorded in the previous scriptures. 'Unlettered' is an ascription to Umm al-Qura (Makkah), which was your birthplace and residence, and where you were appointed to the lofty office of prophethood and messengership. Or, this ascription is to 'umm' (mother), meaning that you did not study in any school or institution, nor did you sit as a student before any teacher. Rather, your nurturer, benefactor, and the one who bestowed knowledge upon you was only your Majestic and Great Lord. And this is a matter of great eminence and a tremendous miracle: without having studied under anyone, you illuminated the world with knowledge. And your students became teachers of the world. Sallallahu alayhi wa sallam.

(2) "He will be a believer" — provided that the basis of his love is that Ali radi Allahu anhu was the cousin of the Messenger, was among the earliest to accept Islam, devoted his entire life to you, participated in all battles, then attained the honor of becoming your son-in-law, and became the fourth caliph. If a person loves him due to some personal relationship, he will not be included under this glad tidings.

(3) "He will be a hypocrite" — provided that his enmity towards Ali radi Allahu anhu is due to those very characteristics mentioned above. If the displeasure is due to some personal dispute, then he will not fall under this warning.

Benefit:
The status of all the noble Companions (radi Allahu anhum) is established in the Qur’an and Hadith. Love for all the Companions (radi Allahu anhum) is a part of faith. A Muslim never goes to extremes regarding any Companion; rather, he has love for each one of them. In this hadith, the love for Sayyiduna Ali (radi Allahu anhu) is mentioned, and all praise is due to Allah, all Muslims have love for him.

In the benefits of this hadith, Mawlana Ataullah Sajid (rahimahullah) writes: By love is not meant the extremism that is found among some people of innovation, for example, some have declared Sayyiduna Ali (radi Allahu anhu) to be infallible like the Prophets (alayhimussalam); some have considered him superior to Sayyiduna Abu Bakr and Umar (radi Allahu anhum); some attribute divine attributes to him, and some have even declared him to be God, who descended to earth in human form.

Similarly, making vows or offerings in the name of Sayyiduna Ali (radi Allahu anhu), calling upon him in times of hardship and difficulty, chanting slogans such as “Ya Ali, Ya Ali madad,” reciting invocations like Nad-e-Ali, or making the shape of a hand with five fingers and considering it to be the hand of Sayyiduna Ali (radi Allahu anhu) and believing it to be a means of resolving difficulties—all these are acts of shirk (polytheism). Sayyiduna Ali (radi Allahu anhu) neither commanded these acts nor is he pleased with them. These matters have no connection whatsoever with that love which is a sign of faith. (Sunan Ibn Majah, Translated: 1/181, Darussalam Edition)

No one should dare to comment or criticize the differences that occurred among the noble Companions. Allah, the Exalted, is pleased with all the noble Companions (radi Allahu anhum), and all praise is due to Allah.